1. Field of the Invention
The invention relates to an intervertebral implant according to the preamble of claim 1, to a kit according to the preamble of claim 41 and to a method for replacing or repairing intervertebral disks according to the preamble of claim 44.
Low back pain is a common disease for example caused by herniated discs, compressed nerve roots, degenerative discs or joint disease. If a patient has this severe pain and does not respond to conservative treatment, spinal fusion is an option to eliminate the pain. Spinal fusion is a surgical technique, wherein two or more vertebrae are joined together. Spinal fusion interventions are also performed to correct back deformities.
With inter-body fusion often an intervertebral spacer or device is placed between the involved vertebrae after removal of the intervertebral disc. The intervertebral device corrects the spine alignment and restores the disc height.
Common intervertebral devices are made from titanium alloys or polyetheretherketone (PEEK). Often these devices comprise pockets that can be filled with bone graft material or artificial graft substitute. The fusion itself takes place when the bone of the endplates grows into and through the intervertebral device. Finally both vertebrae are grown together. Often, additionally, a pedicle system provides additional posterior stabilisation. Intervertebral fusion devices can be implanted with various approaches, for example from the anterior, the posterior or the lateral side.
Over the past years minimal invasive techniques have been introduced. The advantages of the minimal invasive techniques are less soft tissue trauma resulting in a faster recovery. Other complications are reduced as well. In minimal invasive techniques the implant is brought into position between the vertebrae through a small incision with small instruments. Still the intervertebral device must have a sufficient large foot-print to translate the forces between the vertebrae before complete fusion has taken place. If a device is too small, it will sink into or break through the endplate of the vertebra, and the initially restored height is lost.
2. Description of the Related Art
US 2012/0197299 A1 (Henry Fabian JR) describes an implant comprising two members being pivotal relative to each other in a scissor-like manner and each comprising two limbs. The implant may be inserted into a vertebral space in a first non-expanded configuration, where all limbs are adjacent to each other, and which may then subsequently be deployed to a second expanded configuration having a larger foot-print.
US 2013/0079883 (Micheal Butler et al.) describes a radially expandable intervertebral implant including a plurality of filigree members that are interconnected and a deployment mechanism arranged on one end of the link chain.
These known implants have the disadvantage that they comprise either a number of articulations arranged between the interlinked members or a relatively complicated articulation mechanism is necessary to couple the two scissor-like deployment members both resulting in a reduction of the rigidity and compactness of the implant.